Core B: The Cell Culture/Adeno/Lentivirus Core is a Service Core which will: 1) Grow and maintain specialized cell lines to be used by multiple investigators. 2. After infection, maintain epithelial cell lines with adenoviral constructs for acute studies and lentiviral constructs. 3. Keep list of all cells maintained in culture computerized. 4. Assign costs to PPG investigators for use of Core resources (provision of cells, adenovirus, lentivirus etc.). 5. Provide small amounts of cultured cells to other investigators both within and outside of Hopkins for pilot experiments (charge-back to be used). 6. Provide cells/reagents of PPG investigators to scientists around Hopkins and outside Hopkins (cells, antibodies, cDNAs, etc.). 7. Although the Core is largely a Service Core, it also will continue to serve a more minor role to train investigators in using epithelial cells in culture. 8. Provide adenovirus constructs for transient infection studied and lentiviral constructs to make stable lines. This requires engineering, growth, purification and titering.